I actually kinda like Star Trek Enterprises "Affliction" and "Divergence" two parter. People complain about this episode and I've never understood why. For years-nay-decades some fans complained about the Klingons in the movies/TNG/DS9/VOY/ENT looking different than those in TOS. Many of these same fan bitched and complained when Enterprise explained the difference in the two parter as a failed attempt by the Klingons to genetically improve themselves with Human augment DNA (a-la Khan). I actually thought this was a really good explanation for the change. It's creative for sure, it doesn't break canon, and it fits into the Klingon mindset (honor and strength, feeling that using human DNA in their own DNA and the fact that it caused them to lose their cranial ridges and look more human would make them look and feel weaker and would be seen as dishonorable). This also works perfectly with Worfs statement in DS9s "Trials and Tribble-ations" that "we do not discuss it with outsiders". Since seeing it when it first aired 20 years ago I've always thought that this was a satisfactory answer to the age-old Klingon appearance question. There's nothing in the episode that is bad, the overall story is fine, it's fun to see the NX-02 Columbia, there's some good Trip/T'Pol stuff and the episode builds some good new Klingon lore (see above). If anything the only issue I have with this episode is the use of "proto Section 31". I really don't see why people hold a non issue and the answer to a long standing lore question against this episode.
